Method of purifying sugar solutions



` Dec. 6, 1932. c. EBERT ET AL METHOD OF PURIFYING SUGAR SOLUTIONS Filed June 15. 1927 Patented Dec. 6, 1932 I UNITED -sTATl-:s PATENT fol-Flo CHARLES EBERT, OF LEONIA, NEW JERSEY, WILLIAM IB. NEWKIRK, OF RIVERSIDE, ILLINOIS, AND MEYER MOSKOWITZ, 0F SPRING VALLEY, NEW YORK, ASSIGNORS TO INTERNATIONAL PATENTS-DEVELOPMENT COMPANY, OF WILMINGTON, DELA- WARE, A CORPORATION 0F DELAWARE METHOD 0F PURIFYING SUGAR SOLUTIONS Application led June 15, 1927. Serial No. 199,009.

Our invention relates to the removal from ranged so that the outflow through pipe 21 starch converted dextrose solutions of imis from the bottom of the cell. 23 is an outpurities such for example as th-e metallic iiow pipe from the upper part of compartcompounds, fats, proteins, or colloidal subment 11. l stances formed by contact of the solution, The impurities in a starch converted dexor the starch from which the solution is made,4 trose solution comprise colloids forme-d largewith metallic surfaces, piping, vats, copper vlly by the action of the hydrolyzing acid used converters, and the like, and by the reaction for conversion on the non-starch substances of the hydrolyzing acid with n on-starch subin the starch, particularly fats, proteins and stances in the starch used in the conversion. cellulosic material, together with metallic The term starch converted dextrose solucompounds resulting from contact of the mations7 is intended to include converter liquors terial With metallic surfaces, such as the copeither at the end of the conversion or at any per of the converters, and the iron of piping intermediate stage thereof,'hydrols or mother and vessels through which the converted liqliquors obtained from crystallized dextrose uor or the starch from whichit is made, may magmas by centrifuging, pressing or otherhave passed. The colloidal particles, or at wise, and in fact all dextrose containing liqleast a considerable quantity of them, carry uors derived from starch by hydrolysis and positive charges of electricity. When an electaken from the process at any stage, together tric current is passed through the cell these with mixtures of all such liquors including reparticles migrate to the cathode and coming melts. in contact therewith lose their charge and are Our present invention has for its primary coagulated and precipitate-d. The salts of object to provide electrolytic and osmotic th-e heavy metals are in a state of ionization methods of coagulating and precipitating in the solution and under the influence of the and separating impurities from solutions of electric current the negatively charged acid this character. radicals or ions pass through the diaphragm The drawing appended hereto illustrates, 13, (which acts as a barrier, to a very considsomewhat diagrammatically, an apparatus erable extent ,at least, against the passage for carrying out the method. o the dextrose) and migrate toward the The drawing represents a vertical sectional anode 15, the water in compartment'll servview of an electrolytic and osmotic cell for ing as a medium. The metals or hydroxides carrying out the method of our present inof metals, which are positively charged, mivention. l grate toward the cathode and ultimately hy- Referring to the drawing, 10 is a vessel droxides of these heavy metals (copper, iron, divided into two compartments 11 and 12 by aluminum, etc.) are formed, which will be a permeable diaphragm 13, preferably of unprecipitated. l glazed porcelain or other suitable material. The elimination of the acid or negatively The diaphragm should be suiiiciently porous charged ions ofthe above mentioned salts and with a source of current supply 1 8. 19 is a 'from compartment 12 and 22 a partition aritating impurities. But as alkalies react 100 to allow certain substances to pass through it of the hydrolyzing acid from the compartand sufficiently dense to prevent others from ment 12 decreases the hydrogen ion concenpassing, at least in substantial quantities, as tration'of the sugar liquor in this compartwill be hereinafter described. Arranged in ment (increases the pH value) and/this ref the compartments 11 and 12 are the electrodes duction of acidity brings about a further of the cell, 15 designating the anode and 16 coagulation and precipitation of colloidal the cathode, which are connected by wire 17 impurities.

It has been customary to bring about a pipe for introducing the sugar solution into reduction in the acidity of glucose (dextrose) compartment 12. 20 is a Water supply leadsolutions of one kind or another by the use of ing to compartment 11. 21 is an overow neutralizing agents for the purpose of precipwith dextrose, there is a limit to the extent to which they may be used. It is not ossible to bring a dextrose solution to anything like the neutral point by the use of alkalies. Ac` cording to the present method the reduction in acidity, and consequently the purification of the solution, may be carried much further without detriment to the dextrose in the solution.

The fresh dextrose solution flows in constantly, according to the preferred operation of the process, while the treated solution with its impurities in a flocculated and insoluble condition is displaced constantly through the pipe 21, by which pipe the liquid is conducted to any suitable form of filtering apparatus (not shown) consisting either of mechanical filters or bone char filters, 0r both. The solution thus purified may be crystallized for a yield of high purity dextrose in crystalline form, or may be cast in molds or on the casting floor for block sugar, or it may be reconverted in order to increase its purity (dextrose content) and then crystallized, or with or without further conversion, the solution may be used as syrup.

The acidified Water from compartment ll of the electrolytic cell which may contain some dextrose, can be'used for acidifying starch for later conversion.

We claim:

Method of purifying a starch converted dextrose solution which consists in introducing the solution into and withdrawing it from the cathode side of an electrolytic cell having a permeable barrier between its electrodes and introducing water into and Withdrawing it from the cell on the other side of the barrier and ltering the dextrose solution Withdrawn from the cathode side to remove coagulated and precipitated impurities.

CHARLES EBERT. WILLIAM B. NEWKIRK. MEYER MOSKOVVITZ. 

